A ladder foot commonly comprises a U-shaped shoe pivotally coupled by a pin to the bottom of a rail of a ladder in a manner whereby the shoe is angularly adjustable between flat, toe-down and intermediate positions. In the flat position, the bottom of the shoe rests on the ground or other footing to provide maximum adhesion to smooth, flat, surfaces such as asphalt, wood, concrete, etc. In the toe-down position, the shoe is tilted to have its front part contact the ground and serve as a pick like device to provide maximum penetration and thereby holding power on ice or hard, soft, sandy, or frozen earth.
In the past, it has been a common practice for the shoe of a ladder foot to be coupled to a rail of the ladder by a pin-and-slot coupling wherein the pin is passed laterally through a hole in the rail to be translationally fixed in relation thereto, and wherein the pin has opposite ends projecting out from laterally opposite sides of the ladder rail, and those opposite ends of the pin are received in two slots respectively formed in the two sidewalls of the U-shaped shoe. A ladder foot with such kind of coupling is shown, for example, in U.S. Pat. No. 2,691,479 issued Oct. 12, 1954 in the name of J. E. Sharp.
A ladder foot of such construction has, however, a number of disadvantages for use in present day ladders including, without restriction, the following.
To provide ladders which are inexpensive, light in weight and durable, the rails thereof are at present often in the form of lengths of fiberglass of U-shape in cross section so as to have a central, longitudinal elongated relatively thin web and, also, two longitudinally elongated side flanges projecting out in the same direction from the opposite sides of the web. Such rails do not lend themselves readily to a pin-and-slot coupling of a shoe to the rail wherein the two slots are in the shoe and the pin passes through a hole in the web of the rail to be translationally fixed in relation thereto. That is so, because, in view of the thinness of the fiberglass web, it would be difficult to maintain the bolt fixed in its normal alignment to the web and, because in view of such web thinness and the lack of mechanical strength of the fiberglass web (as compared to, say, the metal web of an aluminum rail or the solid thickness of a wooden rail), the transmission of half the weight of the ladder and its occupant from the web to the pin would create undue stresses in the region of the web near the pin.
As another consideration, the provision of pivotally mounting the shoe to the ladder rail by a pin-and-slot coupling wherein slots are formed in the sidewalls of the shoe has the disadvantage that the slots take up substantial space in the shoe's sidewalls in which formed, and such slots must, of course, each be surrounded by sufficient thickness of sidewall material throughout the length of the slot to withstand the mechanical strain imposed on each sidewall when the shoe is bearing substantial weight. This means, however, that each ot the sidewalls of the shoe must be larger in dimension than is really necessary.
Further, in pin-and-slot couplings in the past of ladder shoes to ladder rails, the arrangement was such that, although the shoe when in toe-down position was locked in that position so long as weight from the ladder was on the shoe, the shoe did not remain so locked if momentarily relieved of such weight as, say, by a lifting of the ladder by a slight amount in order to make a small adjustment in its position. Thus, it was often necessary after such an adjustment to reset the shoe to toe-down position, and to have to do so was, of course, an inconvenience.